Originally Posted by dobsy:
“It's science fiction, there's a lot of weird, made up names/things use them in the future if you so desire.
Personally, I wouldn't be surprised if we didn't hear any of them mentioned again at all. Take the return of the Time Lords for example... if SM had wanted them in the next series, they would have stayed. I think he's got a shed load of his own ideas to work with.”
However, as you say, it's Sci-Fi. no reason why SM can't bring them back again if he wants, one, two, or all of them. They've been introduced to the more recent dr who audience now, so it's seeded for future use, and I expect they will be, one day.